Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken

["erich" <erich@areca.com.tw>]

Dear Randy.Dunlap,

Thanks for your new update information.
The ARCMSR_MAX_XFER_SECTORS has bug if its value equal to 4096.
I had change ARCMSR_MAX_XFER_SECTORS of arcmsr linux driver into 512 at last 
driver version.
I will find out the solution and implement it into 4096.

Best Regards
Erich Chen

----- Original Message ----- 
From: "Randy.Dunlap" <rdunlap@xenotime.net>
To: "erich" <erich@areca.com.tw>
Cc: <dax@gurulabs.com>; <billion.wu@areca.com.tw>; <viro@ftp.linux.org.uk>; 
<akpm@osdl.org>; <matti.aarnio@zmailer.org>; <linux-kernel@vger.kernel.org>; 
<James.Bottomley@steeleye.com>; <ccaputo@alt.net>
Sent: Wednesday, April 26, 2006 12:02 AM
Subject: Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken


> On Tue, 25 Apr 2006 16:45:18 +0800 erich wrote:
>
> > Dear Randy.Dunlap,
> >
> > If it is true, I will add sg count check in arcmsr.
> > Driver report : host->sg_tablesize=ARCMSR_MAX_SG_ENTRIES to linux scsi 
> > host
> > layer.
> > But got an incorrect request of sg list count from .queuecommand.
> > Could you tell me which value of ARCMSR_MAX_XFER_SECTORS (4096/512)?
>
> Hi Erich,
> I didn't see 70 sg pieces while using the arcmsr driver, it was
> while testing another driver.  Sorry if that wasn't clear.
>
> Driver setting host->sg_tablesize should be good enough according
> to Documentation/scsi/scsi_mid_low_api.txt .  Are you seeing problems
> with that?  and I don't understand your last question about
> ARCMSR_MAX_XFER_SECTORS.
>
>
> > Best Regards
> > Erich chen
> >
> > ----- Original Message ----- 
> > From: "Randy.Dunlap" <rdunlap@xenotime.net>
> > To: "erich" <erich@areca.com.tw>
> > Cc: <axboe@suse.de>; <dax@gurulabs.com>; <billion.wu@areca.com.tw>;
> > <viro@ftp.linux.org.uk>; <akpm@osdl.org>; <matti.aarnio@zmailer.org>;
> > <linux-kernel@vger.kernel.org>; <James.Bottomley@steeleye.com>;
> > <ccaputo@alt.net>
> > Sent: Thursday, April 20, 2006 11:38 PM
> > Subject: Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken
> >
> >
> > > On Thu, 20 Apr 2006 16:11:04 +0800 erich wrote:
> > >
> > >> Dear Dear Jens Axboe,
> > >>
> > >> Thanks for your notification and advice.
> > >> Areca's firmware has max sg entries of 38 limit.
> > >> In my debug driver I had add this condition check.
> > >> But no one request more than 38 sg.
> > >
> > > Yesterday I saw a request with 70 sg pieces.  It was while
> > > running mkfs.ext3 .
> > >
> > >> Both transfer length all have a lot of requests equal with 38 sg.
> > >> But why it ocur only at 4096 sectors?
> > >> If the /sys/block/sda/queue/max_sectors_kb equal 256 all operation
> > >> running
> > >> well.
> > >> But if I modify it more than 256, the bug appeared.
> > >> I  will do more research about why there were a lot of requests equal
> > >> with
> > >> 38 sg in all file system.
> > >> And only it ocur at the volume that format with mkfs.ext2.
> > >> Thanks again.
> > >>
> > >> Best Regards
> > >> Erich Chen
> > >>
> > >> ----- Original Message ----- 
> > >> From: "Jens Axboe" <axboe@suse.de>
> > >> To: "erich" <erich@areca.com.tw>
> > >> Cc: <dax@gurulabs.com>; <billion.wu@areca.com.tw>; "Al Viro"
> > >> <viro@ftp.linux.org.uk>; "Andrew Morton" <akpm@osdl.org>; 
> > >> "Randy.Dunlap"
> > >> <rdunlap@xenotime.net>; "Matti Aarnio" <matti.aarnio@zmailer.org>;
> > >> <linux-kernel@vger.kernel.org>; "James Bottomley"
> > >> <James.Bottomley@steeleye.com>; "Chris Caputo" <ccaputo@alt.net>
> > >> Sent: Thursday, April 20, 2006 2:42 PM
> > >> Subject: Re: new Areca driver in 2.6.16-rc6-mm2 appears to be broken
> > >>
> > >>
> > >> > On Thu, Apr 20 2006, erich wrote:
> > >> >> Dear Jens Axboe,
> > >> >>
> > >> >> I  do "fsck -fy /dev/sda1" on driver MAX_XFER_SECTORS 512.
> > >> >> The file system was not clean.
> > >> >> I attach mesg.txt for you refer to.
> > >> >>
> > >> >> =====================================
> > >> >> == boot with driver MAX_XFER_SECTORS 4096
> > >> >> =====================================
> > >> >> #mkfs.ext2 /dev/sda1
> > >> >> #reboot
> > >> >> =====================================
> > >> >> == boot with driver MAX_XFER_SECTORS 512
> > >> >> =====================================
> > >> >> #fsck -fy /dev/sda1
> > >> >> /dev/sda1:clean,.............
> > >> >> #reboot
> > >> >> =====================================
> > >> >> == boot with driver MAX_XFER_SECTORS 4096
> > >> >> =====================================
> > >> >> #mount /dev/sda1 /mnt/sda1
> > >> >> #cp /root/aa /mnt/sda1
> > >> >> #reboot
> > >> >> =====================================
> > >> >> == boot with driver MAX_XFER_SECTORS 512
> > >> >> =====================================
> > >> >> #fsck -fy /dev/sda1
> > >> >> /dev/sda1: no clean,........and dump message such as the attach 
> > >> >> file
> > >> >> mesg.txt.
> > >> >
> > >> > So the conclusion is that your driver and/or hardware corrupts data
> > >> > when
> > >> > you set MAX_XFER_SECTORS too high. I can't help you anymore with 
> > >> > this,
> > >> > you should be in the best position to debug the driver and/or 
> > >> > hardware
> > >> > :-)
> > >> >
> > >> > It could be that the higher setting just exposes another transfer
> > >> > setting bug, like maximum number of segments or segment size, etc.
> > >> >
> > >> > -- 
> > >> > Jens Axboe
> > >> >
> > >>
> > >>
> > >
> > >
> > > ---
> > > ~Randy
>
>
> ---
> ~Randy 

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